Shielded lid heater assembly

ABSTRACT

A shielded lid heater lid heater suitable for use with a plasma processing chamber, a plasma processing chamber having a shielded lid heater and a method for plasma processing are provided. The method and apparatus enhances positional control of plasma location within a plasma processing chamber, and may be utilized in etch, deposition, implant, and thermal processing systems, among other applications where the control of plasma location is desirable. In one embodiment, a process for tuning a plasma processing chamber is provided that include determining a position of a plasma within the processing chamber, selecting an inductance and/or position of an inductor coil coupled to a lid heater that shifts the plasma location from the determined position to a target position, and plasma processing a substrate with the inductor coil having the selected inductance and/or position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/793,501 filed Mar. 11, 2013 which is a divisional of U.S. patentapplication Ser. No. 12/408,348 filed Mar. 20, 2009 which claims benefitof U.S. Provisional Application Ser. No. 61/038,510 filed Mar. 21, 2008,all of which are incorporated by reference in their entireties.

BACKGROUND Field

Embodiments of the present invention generally relate to semiconductorsubstrate processing systems. More specifically, the invention relatesto a shielded lid heater assembly for a plasma processing system.

Background

In manufacture of integrated circuits, precise control of variousprocess parameters is required for achieving consistent results within asubstrate, as well as the results that are reproducible from substrateto substrate. As the geometry limits of the structures for formingsemiconductor devices are pushed against technology limits, tightertolerances and precise process control are critical to fabricationsuccess. However, with shrinking geometries, precise critical dimensionand etch process control has become increasingly difficult.

Many semiconductor devices are processed in the presence of a plasma. Ifthe plasma is not uniformly positioned over the substrate, processingresults may also by non-uniform.

Although conventional plasma processing chambers have proven to berobust performers at larger critical dimensions, existing techniques forcontrolling the plasma uniformity are one area where improvement inplasma uniformity will contribute to the successful fabrication of nextgeneration, submicron structures, such as those having criticaldimensions of about 55 nm and beyond.

The inventors have discovered that improvements to the design of heatersutilized to control the temperature of a lid of the processing chamberhave a beneficial effect on plasma uniformity.

SUMMARY

Embodiments of the invention generally provide a shielded lid heater.Other embodiments provide a method and apparatus for controlling the lidtemperature of a plasma processing chamber. The method and apparatusenhances positional control of plasma location within a plasmaprocessing chamber, and may be utilized in etch, deposition, implant,and thermal processing systems, among other applications where thecontrol of plasma location is desirable.

In one embodiment, a process for tuning a plasma processing chamber isprovided that include determining a position of a plasma within theprocessing chamber, selecting an inductance and/or position of aninductor coil coupled to a lid heater that shifts the plasma locationfrom the determined position to a target position, and plasma processinga substrate with the inductor coil having the selected inductance and/orposition.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic diagram of an exemplary semiconductor substrateprocessing apparatus comprising a shielded lid heater in accordance withone embodiment of the invention;

FIGS. 2A-B are a schematic cross-sectional views of two embodiments of ashielded lid heater;

FIG. 3 is an isometric view of one embodiment of the shielded lid heaterof FIG. 1;

FIG. 4 is a top view of one embodiment of the shielded lid heater ofFIG. 1;

FIG. 5 is a partial front side view of one embodiments of a shielded lidheater;

FIG. 6 is a partial back side view of one embodiments of a shielded lidheater;

FIG. 7 is a partial side view of another embodiment of a shielded lidheater; and

FIG. 8 is a flow diagram of one embodiment of a method for plasmaprocessing a substrate.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is also contemplated that elements and features of oneembodiment may be beneficially incorporated on other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

FIG. 1 depicts a schematic diagram of an exemplary plasma processingchamber 100 having one embodiment of a shielded lid heater 180 of thepresent invention. The particular embodiment of the plasma processingchamber 100 is shown in FIG. 1 as an etch reactor, but is contemplatedthat the shielded lid heater 180 may beneficially be utilized in othertypes of plasma processing chambers, including chemical vapor depositionchambers, physical vapor deposition chambers, implantation chambers,nitriding chambers, plasma annealing chambers, plasma treatmentchambers, and ashing chambers, among others. Thus, the embodiment ofplasma processing chamber of FIG. 1 is provided for illustrativepurposes and should not be used to limit the scope of the invention.

Processing chamber 100 generally includes a chamber body 110, a gaspanel 138 and a controller 140. The chamber body 110 includes a bottom128, sidewalls 130 and a lid 120 that enclose a process volume. Thesidewalls 130 and bottom 128 are fabricated from a conductive material,such as stainless steel or aluminum. The lid 120 may be fabricated fromaluminum, stainless steel, ceramic or other suitable material.

Process gasses from the gas panel 138 are provided to the process volumeof the chamber body 110 through a showerhead or one or more nozzles 136.In the embodiment depicted in FIG. 1, the processing chamber 100includes a plurality of nozzles 136 positioned along the sidewalls 130of the chamber body and a nozzle 136 centrally mounted below the lid120. The nozzle 136 mounted in the center of the lid 120 may includeindependently controllable radial and down-facing gas outlet ports.

The controller 140 includes a central processing unit (CPU) 144, amemory 142, and support circuits 146. The controller 140 is coupled toand controls components of the processing chamber 100, processesperformed in the chamber body 110, as well as may facilitate an optionaldata exchange with databases of an integrated circuit fab.

In the depicted embodiment, the lid 120 is a substantially flat ceramicmember. Other embodiments of the process chamber 100 may have othertypes of ceilings, e.g., a dome-shaped ceiling. Above the lid 120 isdisposed an antenna 112 comprising one or more inductor coil elements(two co-axial coil elements are illustratively shown). The antenna 112is coupled, through a first matching network 170, to a radio-frequency(RF) plasma power source 118. During plasma processing, the antenna 112is energized with RF power provided by the power source 118 to maintaina plasma 106 formed from the process gasses within in the internalvolume of the chamber body 110.

In one embodiment, the substrate pedestal assembly 116 includes a mountassembly 162, a base assembly 114 and an electrostatic chuck 188. Themount assembly 162 couples the base assembly 114 to the bottom 128 ofthe chamber body 110.

The electrostatic chuck 188 is generally formed from ceramic or similardielectric material and comprises at least one clamping electrode 186controlled using a power supply 128. In a further embodiment, theelectrostatic chuck 188 may comprise at least one RF electrode (notshown) coupled, through a second matching network 124, to a power source122 of substrate bias. The electrostatic chuck 188 may optionallycomprise one or more substrate heaters. In one embodiment, twoconcentric and independently controllable resistive heaters, shown asconcentric heaters 184A, 184B, are utilized to control the edge tocenter temperature profile of the substrate 150.

The electrostatic chuck 188 may further comprise a plurality of gaspassages (not shown), such as grooves, that are formed in the substratesupporting surface of the chuck and fluidly coupled to a source 148 of aheat transfer (or backside) gas. In operation, the backside gas (e.g.,helium (He)) is provided at controlled pressure into the gas passages toenhance the heat transfer between the electrostatic chuck 188 and thesubstrate 150. Conventionally, at least the substrate supporting surfaceof the electrostatic chuck is provided with a coating resistant to thechemistries and temperatures used during processing the substrates.

The base assembly 114 is generally formed from aluminum or othermetallic material. The base assembly 114 includes one or more coolingpassages that are coupled to a source 182 of a heating or coolingliquid. A heat transfer fluid, which may be at least one gas such asFreon, Helium or Nitrogen, among others, or a liquid such as water oroil, among others, is provided by the source 182 through the passages tocontrol the temperature of the base assembly 114, thereby heating orcooling the base assembly 114, thereby controlling, in part, thetemperature of a substrate 150 disposed on the base assembly 114 duringprocessing.

Temperature of the pedestal assembly 116, and hence the substrate 150,is monitored using a plurality of sensors (not shown in FIG. 1). Routingof the sensors through the pedestal assembly 116 is further describedbelow. The temperature sensors, such as a fiber optic temperaturesensor, are coupled to the controller 140 to provide a metric indicativeof the temperature profile of the pedestal assembly 116.

Temperature of the lid 120 is controlled by the shielded lid heater 180.In one embodiment, the shielded lid heater 180 is a resistive heaterenergized by a power source 178. In embodiments wherein the lid 120 isfabricated from a ceramic material, the shielded lid heater 180 may beadhered or clamped to the exterior surface of the lid 120.

FIG. 2A is a partial cross-sectional view of one embodiment of theshielded lid heater 180 disposed on the lid 120. The shielded lid heater180 generally includes a conductive base 202, a heater element 204 andan RF shield 206. The heater element 204 is sandwiched between theconductive base 202 and the RF shield 206. The heater element 204generally includes a resistive element 212 embedded in an electricalinsulator 210. The RF shield 206 substantially prevents the resistiveelement 212 from influencing the orientation of the magnetic andelectrical field lines generated by the antenna 112 passing through thelid 220 so that the plasma 106 may be more accurately positioned withinthe interior volume of the chamber body 110.

The conductive base 202 generally has sufficient mass to provide uniformheat transfer between the heater element 204 and the lid 120. In oneembodiment, the conductive base 202 is fabricated from a metallicmaterial having good heat transfer characteristics, such as aluminum andthe like. The conductive base 202 may have a geometric form suitable toprovide a desired heat distribution to the lid 220.

The RF shield 206 is generally fabricated from a metallic material suchas aluminum. The RF shield 206 may be aluminum foil or plate. In oneembodiment, the RF shield 206 has the same plan form as the conductivebase 202.

Optionally, a thermal insulator 208 may be disposed on the RF shield206. The thermal insulator 208 is generally fabricated from a materialwhich has little influence on the RF magnetic and electrical fields,such as a high temperature elastomer, such as a silicone or other hightemperature foam. The thermal insulator 208 provides protection fromburns that may be received if the lid heater 180 is inadvertentlytouched while at a high temperature.

The conductive base 202, heater element 204 and RF shield 206 may besecured using fasteners, clamped together or held by a suitableadhesive. In one embodiment, the components of the shielded lid heater180 are secured together utilizing a high temperature epoxy.

FIG. 2B is a schematic cross-sectional view of another embodiment of ashielded lid heater 280 which may be utilized in the chamber 100. Theshielded lid heater 280 generally includes a conductive base 282, aheater element 284 and a RF shield 206. An optional thermal insulator208 may be disposed on the RF shield 206. The heater element 284 isconfigured as described above with reference to the heating element 204of FIG. 2A. The conductive base 282 is substantially similar to theconductive base 202 described above, with the addition of a channel 286formed in a top surface 290. The channel 286 is sized to accommodate theheater element 284. The sidewalls 288 of the channel 286 have a heightsufficient such that the heater element 284 is enclosed within thechannel 286 when the RF shield 206 is disposed on the top surface 290 ofthe conductive base 282.

FIG. 3 depicts an isometric view of the shielded lid heater 280. Theshielded lid heater 280 generally includes a first section 302 and asecond section 304. Each section comprises an annular member 300 and aplurality of fingers 308, 318. The fingers 308, 318 extend radiallyinward from the annular member 300. The annular members 300 of thesections 302, 304 have the same radial dimension, such that when coupledtogether, the sections 302, 304 form a generally circular plan form. Thefingers 318 are generally shorter than the fingers 308 and areinterweaved between adjacent fingers 308 to form a spoke-like pattern.

The first and second sections 302, 304 are coupled by at least onebridge connector 310. In the embodiment depicted in FIG. 3, two bridgeconnectors 310, 312 are illustrated. In one embodiment, at least one ofthe bridge connectors, such the bridge connector 312, may include aninductor coil 314. At least one of the bridge connectors 310, 312couples the heater elements 284 disposed in each section 304, 302, suchthat a single lead 316 may be utilized to couple the shielded lid heater280 to the power source 178.

FIG. 4 depicts a top view of the shielded lid heater 280 with the RFshield 206 removed to expose the heater element 284. As shown, theheater element 284 may be stepped along its path so that a greaterdensity of heating capacity is provided. The ends of the heater element284 include contacts 402 to facilitate coupling of the heater elementsof each section 302, 304, as discussed further below. Also illustratedin FIG. 4 are threaded holes 404 formed in the conductive base 282 tofacilitate fastening of the bridge connectors 310, 312.

FIG. 5 is a partial front view of one embodiment of the shielded lidheater 280 illustrating the bridge connector 310. The bridge connector310 generally includes a body 500 having a plurality of holes 502 whichaccommodate fasteners 504. The fasteners 504 engage the threaded holes404 formed in the conductive base 282, thereby securing the sections302, 304 together. The sections 302, 304 may include a step 510 whichengages with a tab 512 to locate the body 500 relative to the conductivebases 282 in a predefined orientation.

The bridge connector 310 additionally includes a plurality of pins 506which project therefrom. The pins 506 are configured to electricallyconnect the contacts 402 formed at the end of the heater elements 284.Although not shown in FIG. 5, the pins 506 couple the resistive elementsof each heater elements 284 disposed in each of the portions 302, 304through the body 500.

Optionally, the body 500 may be comprised of a conductive material whichelectrically couples the bases 282 of the sections 302, 304.Alternatively, the body 500 may be fabricated from an insulator.

FIG. 6 depicts one embodiment of the bridge connector 312. The bridgeconnector 312 is coupled to the sections 302, 304 of the shielded lidheater 280 as described above. Also as discussed above, the bridgeconnector 312 includes an inductor coil 314. The inductor coil 314 maybe sized to provide an inductance tailored to influence the magnetic andelectric fields within the chamber in order to produce a desired effecton the plasma 106. In one embodiment, the inductor 314 is a variableinductor to allow tuning of the inductance value between process runs orin situ processing. The inductor coil 314 may be isolated from theconductive bases 282, or alternatively electrically couple the bases 282through leads 602, 604.

A body 600 of the bridge connector 312 may be conductive as toelectrically couple the conductive bases 282 of the sections 302, 304.Alternatively, the body 600 of the bridge connector may be fabricatedfrom a dielectric material to electrically insulate the sections 302,304.

FIG. 7 is a partial top view of another embodiment of a shielded lidheater 780. The shielded lid heater 780 is generally configured similarto the heaters 180, 280 described above, with the addition of arepositionable inductor 700. The shielded lid heater 780 includes aplurality of mounting holes 702 which allow the inductor 700 may befastened at any number of locations. Thus, the position of the inductor700 along the shielded lid heater 780 may be changed as needed to suitprocesses needs by securing the inductor 700 to a different set ofmounting holes 702.

In one embodiment, the inductor 700 may be electrically isolated fromthe shielded lid heater 780. In one embodiment, the inductor 700 may beelectrically coupled to the conductive base of the shielded lid heater780 either through contact pins, mounting fasteners or other suitablemanner.

FIG. 8 is a block flow diagram of a method 800 for plasma processing asubstrate in a processing chamber equipped with a shielded lid heater.The method 800 begins by determining a position of a plasma within theprocessing chamber at 802. The plasma position may be determined bymeasuring a characteristic of the plasma, by optical methods, utilizingsensors, empirical dates, examination of processing results, modeling orother suitable manner. At 804, an inductance and/or position of aninductor coil coupled to a lid heater is selected which will to shiftthe plasma location from the determined position to a target position.At 806, the substrate is processed in the presence of a plasma with theinductor coil having the selected inductance and/or position. Theprocess performed on the substrate may be selected from the groupconsisting of etching, chemical vapor deposition, physical vapordeposition, implanting, nitriding, annealing, plasma treating, andashing, among other plasma processes.

Thus, a lid heater has been provided that enhances positioning of theplasma within a processing chamber. As the plasma can be positioned in amore desirable location, more uniform and predictable processingrequests may be realized.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A process for tuning a plasma processing chamber,comprising: determining a position of a plasma within a processingchamber; selecting an inductance characteristic of a lid heater disposedon the processing chamber that shifts a plasma location from thedetermined plasma position to a target plasma position; and plasmaprocessing a substrate with the inductor coil having the selectedinductance and/or position.
 2. The process of claim 1, wherein plasmaprocessing further comprises: performing a process on the substrateselected from the group consisting of etching, chemical vapordeposition, physical vapor deposition, implanting, nitriding, annealing,plasma treating, and ashing.
 3. The process of claim 1, wherein the lidheater includes an annular thermally conductive base having a pluralityof inwardly extending fingers forming a spoke-like pattern.
 4. Theprocess of claim 3, wherein the inductor coil is electrically isolatedfrom the conductive base.
 5. The process of claim 3, wherein theinductor coil is electrically coupled to the conductive base.
 6. Theprocess of claim 1, wherein determining the position of the plasmacomprises: measuring a characteristic of the plasma, by optical methods,utilizing sensors, empirical dates, examination of processing results,modeling or other suitable manner.
 7. The process of claim 1, whereinselecting the inductance characteristic comprises: varying theinductance value of a variable inductor between process runs or in situprocessing to produce a desired effect on the plasma, wherein thevariable inductor is sized to provide an inductance tailored toinfluence the magnetic and electric fields within the chamber.
 8. Theprocess of claim 1, wherein selecting the inductance characteristiccomprises: changing an inductance of the inductor coil.
 9. The processof claim 1, wherein selecting the inductance characteristic comprises:changing a position of the inductor coil.
 10. A process for tuning aplasma processing chamber, comprising: plasma processing a firstsubstrate in the processing chamber, the processing chamber having aheater disposed on a lid of the processing chamber, the heater having atunable inductance characteristic; and plasma processing a secondsubstrate in the processing chamber while heater has an inductancecharacteristic different than an inductance characteristic of the heaterwhen processing the first substrate.
 11. The process of claim 10 furthercomprising: determining a position of a plasma within the processingchamber while processing the first substrate; and selecting aninductance of an inductor coil coupled to a heater that shifts a plasmalocation from the determined plasma position to a target plasmaposition.
 12. The process of claim 10 further comprising: determining aposition of a plasma within the processing chamber while processing thefirst substrate; and selecting a position of an inductor coil coupled toa heater that shifts a plasma location from the determined plasmaposition to a target plasma position.
 13. The process of claim 10,wherein plasma processing the first substrate further comprises:performing a process on the substrate selected from the group consistingof etching, chemical vapor deposition, physical vapor deposition,implanting, nitriding, annealing, plasma treating, and ashing.
 14. Theprocess of claim 10, wherein the lid heater includes an annularthermally conductive base having a plurality of inwardly extendingfingers forming a spoke-like pattern.
 15. The process of claim 14,wherein the inductor coil is electrically isolated from the conductivebase.
 16. The process of claim 10 further comprising: measuring acharacteristic of the plasma, by optical methods, utilizing sensors,empirical dates, examination of processing results, modeling or othersuitable manner; and changing the inductance characteristic of theinductor coil in response to the measured characteristic of the plasma.17. The process of claim 10, wherein changing the inductancecharacteristic of the heater comprises: varying the inductance value ofa variable inductor between process runs or in situ processing toproduce a desired effect on the plasma, wherein the variable inductor issized to provide an inductance tailored to influence the magnetic andelectric fields within the chamber.
 18. A process for tuning a plasmaprocessing chamber, comprising: plasma processing a first substrate inthe processing chamber, the processing chamber having a heater disposedon a lid of the processing chamber, the heater having a tunableinductance characteristic; measuring a characteristic of the plasma, byoptical methods, utilizing sensors, empirical dates, examination ofprocessing results, modeling or other suitable manner; and changing theinductance characteristic of the inductor coil in response to themeasured characteristic of the plasma.
 19. The process of claim 18,wherein changing the inductance characteristic comprises: changing aninductance of the inductor coil.
 20. The process of claim 18, whereinchanging the inductance characteristic comprises: changing a position ofthe inductor coil.